I. Field of the Invention
The present invention relates generally to fluid flow meters and, more particularly, to a fluid meter with new and improved means for providing a seal between the vane member and an internal wall which separates the inlet and outlet ports for the flow meter.
II. Description of the Prior Art
A variety of measuring devices and the like are now available for supplying information regarding the rate of flow in a fluid flow system. One such type of instrument, commonly called a flow meter, comprises a rate flow indicator in which a semicircular vane member is rotatably mounted and movable by fluid flow through the device. The vane member is connected with indicating means to indicate exteriorly of the device the rotational position of the vane member and thus the rate of flow through the device.
As the semicircular vane member is rotated by fluid flowing through the device, it moves along a hemispherical wall section having its pivotal axis offset from the center of the wall section so that pivotal movement of the vane creates an opening between the outer edge of the vane and the wall section. This opening increases in cross-sectional area as the vane moves from a closed and to a maximum open position. In this way, the flow meter does not unduly interfere with the rate of fluid flow through the device.
One problem associated with such flow meters is that the leakage past the edge of a vane member in the area where the vane member is pivotally mounted will seriously impair the accuracy of the device and this is particularly true for high fluid pressure applications. Previous attempts to cure this problem by providing a seal between the vane shaft and the housing oftentimes results in a large amount of friction between the seal and the vane shaft. Such friction in turn inhibits the movement of the vane member and thus adversely effects the accuracy of the flow meter.
One previously known device designed to overcome this problem is disclosed in U.S. Pat. No. 3,776,037, entitled "FLOW INDICATOR DEVICE WITH SEALING MEANS" which issued on Dec. 4, 1973. In this prior patent, a teflon shoe is mounted in a slot formed within the housing so that one edge of the teflon shoe abuts against the vane shaft. Compression springs are also positioned between the housing and the other edges of the teflon shoe and urge the teflon shoe against the vane shaft. While this prior known device has proven effective in use, it is relatively expensive to construct the housing with the necessary receiving slot for the teflon shoe and its associated springs.